Book/Report

FZJ-2018-01543

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Cleaning and conditioning of the walls of plasma devices by glow discharges in hydrogen

Waelbroeck, F.FZJ* ; Winter, J.FZJ* ; Ali-Khan, I.FZJ* ; Wienhold, P.FZJ* ; Brandt, B. ; Dietz, K. J.

1980
Kernforschungsanlage Jülich, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/17524

Report No.: Juel-1692

Abstract: The influence of a number of parameters on the cleaning and preconditioning efficiency of a combined rf and glow (RG) discharge is studied experimentally. The emphasis is laid on problems of oxygen removal from the surface. The important parameters are the wall temperature T$_{W}$, the pump speed Sp, the current I$_{GD}$ of the glow discharge and the hydrogen pressure P$_{2}$. In a device with a ratio Sp/S = 0,1 ms$^{-1}$ (S : inner area), a rapid deoxidation is achieved when T$_{W}$ > 200 $^\circ$C. At room temperature, the oxide layer is reduced from a (carbon-free) surface hen 1 to 2 % of methane is added to the hydrogen : carbon monoxide is formed and evacuated. Admixture of other gases such as He, Ne do not increase the cleaning efffciency. An equation derived from a simplified model describes semi-quantitatively the observed parametric dependances. The tendency for arc Spots to occur during the initial phases of the discharge depends on the preconditioning of the wall : a prolonged bake-out at 200 °C leads to the non-appearance of orcs in all cases examined. Problems arise when a quadrupole residual gas analyser is used to measure the partial pressure of water in hydrogen. These are analysed und a conditioning technique is described which has proven to be appropriate in our measurements.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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